Paris (CNN) -- François Hollande, the newly-inaugurated President of France, may be as notable for what he has not done as for what he has.
He has never held national elective office despite being at the center of French politics for more than a decade, and he has never been married despite a three-decade relationship and four children with Ségolène Royale, another of the country's top Socialist politicians.
Hollande led the Socialist Party for 11 years and was leader when Royale ran unsuccessfully for president against Nicolas Sarkozy in 2007.
Hollande and Royale split up a month before that election, and he is now seeing journalist Valérie Trierweiler, who appeared, smiling with him, as he celebrated his victory Sunday.
He immediately spooked markets, and Germany, France's key ally in the European Union, with his victory speech.
"Austerity can no longer be something that is inevitable," he said, apparently undercutting the belt-tightening that his predecessor and German Chancellor Angela Merkel have urged on European countries beset by debt.
Hollande emerged as his party's candidate for president after the downfall of Dominique Strauss-Kahn, who was once considered the Socialist favorite to defeat Sarkozy.
But Strauss-Kahn was arrested in May 2011 after a New York hotel maid alleged that he tried to rape her. Charges against the former IMF chief were later dropped in the United States, but he has been warned he could be investigated in France over accusations he participated in a prostitution ring.
But Hollande was not an accidental candidate despite the way he has come to power, one commentator said.
"He's been preparing this campaign for 18 months now, much before DSK's demise," journalist Agnès Poirier said, referring to Strauss-Kahn.
"Some say that he knew, like actually many others in the party, that DSK was doomed: His colorful private life was always bound to prevent his running for president," Poirer told CNN before the final vote.
"In that respect, he's not a candidate by default. He's simply a less charismatic personality than DSK and less antagonistic than Sarkozy."
Born in 1954 in the northern city of Rouen, Hollande was the son of a doctor and a social worker. He was educated at the elite Ecole Nationale d'Administration, where he met Royale in 1978.
Hollande has represented the southern Corrèze region in parliament since 1988 but has never held higher elective office than that post.
The 57-year-old's electoral appeal is built around his affability, but the candidate was dogged during the campaign by questions from even within his own party about whether he has the charisma and decisiveness to be president.
Hollande said: "There's always a risk when the candidate becomes president: Will he deliver what is expected of him?
"It's a choice, it's always an important moment for a country because it has to choose between two risks: Either you keep the candidate who is on his way out or take the new candidate that we don't know. It's a gamble."
But after five years of Sarkozy's hyperactive presidency, during which time France's economic status has taken a knock, polls suggested voters were keen for a change from the president's flamboyancy.
Before the first round of voting, former President Jacques Chirac added his support to Hollande, though Chirac was a center-right president, like Sarkozy.
Chirac biographer Jean-Luc Barré told French TV channel BFM TV: "He said last June that he will vote for François Hollande. ... He has said it a few times since and then again 10 days ago."
During the campaign, Hollande admitted that half of those who declare they will vote for him were primarily voting against Sarkozy.
"What the French want is coherence, stability and justice," Hollande said. "If I am in a favorable position today, it's because my fellow citizens want to make the effort to straighten out the country, and at the same time they want it to be just and equitable -- no one left out of national solidarity and no one left out of the contributions which must be made."
To his critics that sounded as if Hollande wants to revive left-wing tax and social policies of the past, a view reinforced in the first speech of his campaign when he attacked the financial community.
"I don't want to drive the markets crazy, I don't want to create trouble but rather order and rules and norms. We have to struggle against financial excesses ... those who speculate with sovereign debt, those who develop financial products which have done so much harm," he said.
But given the constraints of international finance and economic structures, observers said Hollande will not really have room to maneuver to shift France radically to the left.
Hollande has been criticized for declining to spell exactly what his economic policies will be, although he has pledged to increase taxes on the rich, boost social spending and create thousands of state jobs. He has also vowed to renegotiate the eurozone fiscal agreement, but analysts said Hollande will likely be a pragmatic leader.
The word one hears most often to describe Hollande's style is "sympa," French slang for sympathetic, but his victory also owes a great deal to Strauss-Kahn's misfortune.
CNN's Peter Wilkinson and George Webster contributed to this report.